This invention relates to a spectrum display device and method for audio signals, which is capable of displaying a spectrum of an audio signal on a screen of a display unit at real time, and to an analog to digital converter having plural sampling frequencies, each of which is selected as a function of the highest audio frequency applied to the converter.
Since a display device capable of displaying a spectrum of an audio signal on a screen of a display unit at real time can be effectively used for visual confirmation of vividness, adjustment of balance between signals of respective channels within audio devices, and for adjustment of various characteristics of audio devices, research for practical use of display devices of this sort has been carried out hitherto.
As spectrum display devices for audio signals in the prior art, although it has been attempted to provide one having a structure arranged to obtain frequency components of an audio signal by way of a plurality of band pass filters so as to indicate the same on a screen of a display unit, such conventional one is complex in structure, while it has been difficult to provide one having a high resolution at a low cost. For this reason an improvement therefor has been desired.
In order to resolve the above-mentioned problem although effort has been made to provide a new spectrum display device in which spectrum analysis is carried out by way of Fast Fourier Transform (FFT) operation to display the result of the same on a screen of a display unit, it is necessary to execute complex calculations in connection with a number of data when performing FFT operation when it is intended to narrow the interval between frequencies of the spectrum on spectrum analysis, and therefore it takes a long period of time for performing FFT operation resulting in difficulty in real time indication of a spectrum.